The gastric properties of free-ranging harp (Pagophilus groenlandicus (Erxleben, 1777)) and hooded (Cystophora cristata (Erxleben, 1777)) seals

• Published in: ICES Journal of Marine Science
• Main Authors: Christiansen, Jørgen S., Gildberg, Asbjørn, Nilssen, Kjell T., Lindblom, Charlotta, Haug, Tore
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2004
• Subjects: Ecology; Aquatic Science; Ecology, Evolution, Behavior and Systematics; Oceanography; Cystophora cristata; Harp Seal; hooded seal; Pagophilus groenlandicus
• Online Access: http://dx.doi.org/10.1016/j.icesjms.2004.01.002; http://academic.oup.com/icesjms/article-pdf/61/2/287/29159044/61-2-287.pdf

Abstract The study of trophic relationships in seals is based primarily on prey remains recovered from the digestive tract or scats. Basic data on the gastric properties of seals are scarce and are considered to be important to interpret data from dietary studies of these animals. Hence, we examined the key properties of the gastric chyme post mortem (i.e. temperature, acidity, and the concentration of the proteolytic enzyme pepsin) in free-ranging harp (Pagophilus groenlandicus, n=40) and hooded (Cystophora cristata, n=41) seals. Seals displayed huge inter-individual variations in their gastric properties with ranges in temperature: 23.9–37.9°C, acidity: pH 1.16–7.34, and pepsin concentration: 11–1059 μg ml−1 chyme. The stomach weight and the mean values of gastric parameters revealed, however, significant species-specific differences. The stomach weight relative to body weight of hooded seal exceeded that of harp seal (t=13.77, d.f.=75, p<0.001). Furthermore, the gastric temperature and pepsin concentration were lower for harp (32.8°C and 75 μg ml−1) compared to that for hooded (35.3°C and 344 μg ml−1) seal. The reason for this disparity may be linked to the feeding mode and diet composition displayed by these seal species.